1. Technical Field
The present invention relates to fluid systems including electrically operated flow control valve arrangements for use in closed loop systems for pressure relief and fluid make-up.
2. Background
A typical hydraulic system provided with pressure relief may include a solenoid operated check valve with variable relief. Such hydraulic systems may be devised to control the output of a working device such as speed control of a cooling fan, for example. It is known to incorporate at least one valve into the system to prevent overpressure, such as, a relief valve for xe2x80x9cload lockxe2x80x9d (e.g., freezing or locking of the working device). An additional valve has been provided to the hydraulic system for fluid make-up to prevent cavitation damages to the hydraulic system, especially the working device. Cavitation occurs when, for example, the supply pressure becomes less than the discharge pressure resulting in gas formation within the working device. Furthermore it is often necessary to employ an additional valve to a signal circuit of the hydraulic system to compensate for varying signal pressure. The cost to provide the additional valves and controls, in addition to the labor associated with installation, is significant.
An embodiment of the present invention provides a fluid control system including a pressure supply and a valve arrangement including an inlet and an outlet and being in fluid communication with the pressure supply. The valve arrangement includes a relief operator being configured to provide fluid communication between the inlet and the outlet of the valve arrangement in response to a predetermined pressure condition at the inlet. The valve arrangement is configured to provide fluid communication between the inlet and the outlet of the valve arrangement in response to an outlet pressure being greater than an inlet pressure.
The present invention further provides a valve arrangement including a body having an inlet and an outlet and a relief operator provided in the body. The valve arrangement is configured to provide fluid communication between the inlet and the outlet of the body in response to a predetermined pressure condition at the inlet. The relief operator is configured to provide fluid communication between the inlet and the outlet in response to an outlet pressure being greater than an inlet pressure.
The valve arrangement provides for pressure relief, and additionally, provides make-up fluid without the use of multiple valves and controls.